Firearm



Oct. 13, 1931. I J. D. PEDERSEN 827,037

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FIREARM Original Filed Jul 18. 1928 10 Sheets-Sheet 10 f? INVENTOR.

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Patented Get. 13, 393E aerate? rarer car es JOHN D. PEDEBSEN, OF SlPBmGFIE-LD, MASSACHUSETTS imam Application filed July 18, 1928, Serial This invention relates to improvements in firearms, more particularly guns of the bolt action type, and has to do with an automatic mechanism in such a gun.

An object of the invention is to provide an automatic action for a gun having a rotary and reciprocatory bolt, with power storing mechanism and firing mechanism containabl e in a receiver of normal dimensions, viz. substantially the same as of a standard hand operated gun. A further object is to simplify such mechanisms and attain a smooth-running automatic action which will operate efficiently and with certainty under the most severe conditions of use.

The power for the automatic action is obtained from the backward pressure of the fired cartridge against the face of the bolt, the barrel being fixed to the receiver. In utilizing this power, provision is made for initially delaying the opening of the bolt in large part by a. force in inertia, whereby the resistance offered by recoil springs or friction is of minor consequence and variation in friction 95 due to lubricated or unlubricated surfaces will not be the controlling element in determining operation or non-operation of the gun.

In order to avoid the use of large masses for inertia which would unduly weight the gun, I have taken advantage of the moment of inertia of a rotary bolt. In the present invention, this is made efiective for absorbing a large amount of the firing pressure energy by a high rotative acceleration imparted to the bolt at the initial opening and a long ra- (lius of gyration for the bolt obtained by a weight which may be comparatively small and located at the outer end of the bolt handle.

The bolt is held to its breech closed position by locking means which act automatically in unlocking the bolt and in combination with the moment of inertia of the bolt prevent a too rapid initial opening of the bolt under the force of the firing pressure. The

locking means comprises a helical bearing surface or looking cam in the receiver for coaction with a locking lug on the bolt, whereby the firing pressure will automatically un- No. 293,537. Renewed March 3, 1931.

lock the bolt and give rotation to the bolt for openmg.

The efliciency of the helix angle of this bearing surface will determine not only the amount of firing pressure energy dissipated 1n friction against the locking cam, but also the rotative acceleration imparted to the bolt and the energy absorbed thereby, the friction dissipation varying inversely and the rota-. tive acceleration varying directly with the helix angle efliciency. (Helix angle efficiency is here derived by the same formula as for the efficiency of screw threads.) A helix angle no greater than the angle of repose for the bearing surface will of course have zero efliciency since in that event the bolt lug would look permanently against the locking cam under any firing pressure. Accordingly, I have adopted for the bearing surface, or locking cam, a helix angle of relatively high efficiency and one considerably larger than the angle of repose for either lubricated or dry surfaces so as to insure that the bolt will open under either condition. A further advantage in the use of a helix angle of high efliciency is that the amount of energy delivered to the bolt for the operation of the breech mechanism will not differ widely between lubricated surfaces and dry surfaces and thus a more uniform action of the mechanism will be obtained under all circumstances.

I have determined experimentally that the angle of repose for such metal surfaces when lubricated is approximately 7 30' and for dry surfaces approximately 15. The referred helix angle for the locking cam o the present gun is approximately. 30, and this I believe is a radical departure from any hitherto known practice in gun design. The use of a helix angle of such high efliciency is made practical in the present gun'by the presence of a large moment of inertia 1n the bolt and handle, as previously described. The

-inthe receiver facing operating the breech mechanism a with the surfaces oiled would deliver approximately such proposed construction, the bearing surface has a helix angle of very low efficiency so as to dissipate all but a small part of the firing pressure energy in friction. In such construction, the helix angle proposed is only slightly greater than the angle of repose for the bearing surface when well oiled, with the result that if the surface becomes dry or unlubricated it would then permanently lock the bolt against the firing pressure and prevent its automatic opening because of the fact that the angle of repose for the dry surface would be greater than the helix an le employed. In other words, a dry locking cam of such low helix angle efliciency would render the gun non-automatic in its action. A. helix angle of low efficiency as described, while useful in the dissipation of ener by friction, has the great disadvantage 0 requiring that the surfaces be uniformly lubricated at all times, because its efliciency and the working power delivered to the bolt varies greatly with proportionately slight differences in lubrication. In the present invention, on the other hand, a lack of lubrication will make little noticeable difierence in the operation of the gun.

A further feature of improvement in the resent invention resides in a special conormation of the guiding cam which guides the bolt from its rotary movement into its rectilinear movement. This guiding cam is the locking cam at the opposite side of the ing surface beginning as a helix of approximately the same helix angle as the locking cam and fairing into a translation curve of the more favorable shape for the transition of the-bolt into its rectilinear path. The translation curve is carefully designed for an even distribution of friction losses and working energy from the bolt so as to produce a smooth working travel thereof during the opening cycle.

Combined with the foregoing are other improved features in the gun residing in novel and compactly arranged closing means for the bolt, buffer mechanism and firing mechanism, the details and advantages of which will be clearly apparent in the following description taken in connection with the accompanying drawings.

It will beunderstood that the complete gun comprises a wooden frame or stock and a barrel of suitable construction, ,but these olt lug and has a guid-' arts, not being essential for illustrating the Invention, are omitted from the drawings:

hFig. 1 is a side elevation of the receiver of t e ing 111 full lines the bolt and bolt handle in breech closed position and in dotted lines the handle, after the bolt has rotated through 90 and moved to the rear; 4

Fig. 2 is a top plan view of the receiver shown in Fig. 1

Fig. 3 is a perspective view-of the receiver with all its contained parts removed; v Fig. 3a is a diagram illustrating the form of the path taken by the extremity of the radius of gyration of the bolt during its change from rotary to rectilinear movement, said path being unrolled from an imaginary cylindrical surface on to a plane surface; and also the form of the path taken by a point of the bolt in actual contact with the guiding cam of the receiver when said ath is unrolled from the cylindrical wall of t e receiver onto a plane surface. These paths are takenthrough 90 of bolt rotation;

Fig. 4 is a side elevation of the working parts in the receiver as shown with-the right side of the receiver cut away, the bolt being rearward at its stopped position;

Fig. 5 is a similar view with the bolt in its forward breech closed position;

Fi 6 is anothersimilar view but having the right side of the slide also cut away along line 6-6 of Fig. 7 to show the secondary closing spring. In this view the hammer is shown in fired position; i

Fig. 7 is a transverse section through the receiver and arts contained therein along line 77 of. ig. 4;

Figs. 8, 9 and 10 are perspective views of the bolt, bolt carrier, and slide, respectively;

Fig. 11 is a fragmentary perspective of the bolt at its forward end and the upper side thereof at the left of the bolt lug;

Fig. 12 is a fragmentary erspective of the face of the bolt and the und er side of the bolt at the right of the bolt lug;

Fig. 13 is a longitudinal section of the bolt showing the mounting of the firing pin and extractor therein;

Fig. 14 is a perspective of the buffer spring;

Fig. 15 is a perspective of the buffer spring retainer;

Fig. 16 is a perspective of the trigger;

Fig. 17 is a perspective of the sear;

Fig. 18 is a perspective of the hammer;

Fig. 19 is a perspective of the hammer spring guide;

Fig. 20 is a perspective of the hammer spring container or bridge member; 7

Fig. 21 is a perspective of the bolt stop;

Fig. 22 is a perspective of the bolt stop actuator;

. Fig. 23 is a perspective of the follower rear supporting lever;

n and parts assembled therein, show- Fig. 24 is a perspective of the follower front supporting lever;

Fig. is a perspective of the follower; Figs. 26 and 27 are detached views of the trigger, sear and hammer assembly in two successive positions to illustrate the escapement action between the sear and hammer; and

Fig. 28 is a fragmentary view in position of the follower rear supporting lever and its actuating spring. 7

Referring more particularly to'the drawings. the metal frame or receiver 1 serves the usual purpose as a supporting Container for the operative parts of the breech a'ction and firing mechanism. The receiver is adapted to be mounted in a wooden stock (not shown) and has secured to its forward end a barrel.

Bolt closing means is the forward slide or bolt carrier 2 having a longitudinal bore 3 therethroughto receive a cylindrical bolt 4. Slidably mounted on top of the forward slide-2 (as shown in Fig. 7) is the rear slide 5. The two slides thus have a telescoping or collapsible relation with one another for a reciprocatory travel in said receiver.

The rear slide 5 has a primary closing spring 6 surrounding sprin guide'7 and interposed between said slide and the back wall of the receiver 1. The spring 6 extends within and is adapted to be housed'in the bore 8 of said rear slide. Interposed between the rear slide 5 and the forward slide or bolt carrier 2 and adapted to be housed in the bore 9 of said bolt carrier is the secondary closing spring 10 surrounding a spring guide 11. The secondary closing spring 10 is purposely made slightly weaker than the primary spring 6 so that upon retraction of the bolt the forward slide or bolt carrier first collapses into the rear slide and then the complete assembly moves rearward.

The bolt 4 is rotatably mounted in the bolt carrier 2 and by means on the receiver, hereinafter described, this rotation is limited to 90 of motion. A driving'connection is rovided between the bolt carrier and the olt consisting of a helical cam surface 12 at the forward end of the carrier coacting with a helical cam surface 13 at the rear upper side of the bolt lug 14 (see Figs. 2 and 11). The bolt lug is located at the forward end of the bolt and a bolt handle 15 is preferably formed as a continuation of said bolt lug, as shown. The outer end of said bolt handle is provided with a weighted knob 16. By means of the cam surfaces 12 and 13, the rotation of the bolt from its closed position (shown in Fig. 2) to its open position (shown in Fig. 4 will cam the bolt carrier 2 to the rear an conversely, the forwardthrust of the bolt carrier by its. closing spring will rotate the bolt back to its closed position. The cam surface 12 of the bolt carrier terminates in a flat portion 17 for coacting with a flat portion 18 on the bolt lug 14 when the bolt handle is vertical so as to provide a neutralposition of restv and thus avoid any tendency toward bolt rotation while the boltis reciprocating with the bolt carrier. Supplementing the driving connection just described is a further interlocking driving connection be tween thebolt and bolt carrier afforded by the helical and interfitting cam cuts 7 19 and 20 on the under portions respectively of the bolt and bolt carrier. These cam cuts likewise terminate in fiat portions 21 and 22 to provide the rest position. When the cam cuts 19 and 20 are interengaged, no rearward movement of the bolt carrier is possible without a rotation of the bolt.

Bolt locking means opening and closing cycle. The initial period during which the force of the-firing pressure is exerted against the face of the bolt and thus moves the bolt backward is termed the power stroke. This period is very brief in time and the power stroke very short in extent so that no chance can occur of the cartridge bursting at the breech.

A locking cam 23, having a helical bearing surface, is provided on the right side of the receiver for coaction with a helical locking surface 24 at the rear of the bolt lug 14 (see Figs. 3 and 8). On the opposite side of the bolt from the lug locking surface 24 are formed two spaced supplemental or guiding lugs 25 and 26 which have helical bearing surfaces 27 and 28 for coacting with helical counter-bearing surfaces 29 and 30 in the left hand wall of the receiver. The pitch of the coacting surfaces 27 and 29, 30 and 28, is the same as that of surfaces 23 and 24, and together said surfaces act in the nature of a screw thread for imparting rotation to the bolt. The clockwise rotation of the bolt 4 is limited by the abutting of its lug 14 upon the horizontal stop shoulder 31 of the receiver right hand wall, and in this position the bolt is closed against the breech.

The bolt is rotatable through 909 from this position under guidance of the helical cam surfaces, above described, and the latter part of this rotary movement is gradually directed into a rectilinear movement of thebolt by p means of the guiding cam 32.

The bearing surface for the lockin cam 23 is of am le proportions to receive t e mam backwar thrust-of the bolt on firing, and ts helical surface is referably chosen to have an eflicient an 1e 0 inclination or helix an le, as distingu' an le or one that would prevent automatic unfockin by the backward thrust of the .bolt. he helix angle here considered is that defined in standard text books, namely the angle which the helical surface makes to a plane helix.) he helix angle of re -ose, below which such helical surfaces wou d lock permanently against thrust, has been found by experiment to be approximately 7 30' for lubricated surfaces, and approximately 15 for dry surfaces. An hing in the close neighborhood of such elix angles for'the bearing surface of a locking cam I would regard as an inefiicient helix angle.

The helix angle adopted for my bearing surface 23 has been preferably chosento be approximately twice the angle of repose for such surfaces when dry, namely about 30, and one effect ofthis is to insure that the bolt will be automatically opened by the firing pressure whether the surfaces be dry or lubricated. Another effect is that a high rotative acceleration is imparted to the bolt during. the power stroke so that suflicient energy will be absorbedby the bolt and moving parts to complete the opening and closing cycle of the breechactionland including the automatic loadingof a fresh cartridge.

A too rapid opening of the bolt during the ower stroke, from such an eflicie'nt helix ang e, is prevented bythe moment of inertia of the rotating-bolt which has been purposely made large by a heavy-bolt handle 15 projecting laterally from the bolt and having at its outer end the weighted knob 16. Both the bolt handle and knob are heavier than required for their simple function as a grasping handle, and the concentration of weight in the knob 16 is for the purpose of providing as long a radius of ration for the bolt as is practicable. By this construction, the radius of gyration of the bolt is extended a considerable distance outside the receiver wall. Consequently this radius of gyration of the bolt is considerably longer than the radius of the helical bearing surfaces which constitute the locking means for the bolt.

viz. the main bearing surface 23 and the sup- 1 plemental bearing surfaces 29 and 30.

After the termination of the power stroke, the bolt continues in its helical motion for about of rotation, and thereafter duringthe remainder of its rotation is diverted into a rectilinear motion. The guiding cam 32 has a guiding surface for accomplishing this change of motion in the bolt and comstraight line ed. from an ineflicient he ix perpendicular to the axis of the rises an initial helical portion 32a fairing into a transition curve portion 32b of somewhat elliptical form carried around to a arallel with the axis of the bolt. The he ical ortion 32a extends for about 70 rotation o the bolt and has a helix .angle about equal to that of the locking cam 23. The most favorable form of the transition curve portion 32?) would be the arc of a circle, if said portion were in guiding contact with the bolt at the end of its radius of gyration; but since, as before stated, the radius of gyration of the bolt extends outside the.receiver, the portion 32b has a form suchas would be developed by the contactin portion of the bolt lug on the actual cy indrical wall of the receiver assuming that the extremity of its radius of gyration were guided in a circular arc'in an imaginary cylinder of a radius equal to the radius of gyration of the bolt. In other words the transition curve is such that the path of contact between the bearing surface 326 and bolt lug 14 during the travel of the lug from its straight path into its helical path, correspon s to the path cut by the intersection of the radius of gyration of said bolt with the wall of the receiver when the path (as projected on a plane surface) of said bolt at the extremity of its radius of gyrationis the arc of a circle. In this way. the bolt is ided so that at the extremity of its radius 0 gyrabetween the bolt and guiding cam 32 as it would appear if unrolled on a'plane surface. The straight part of 51 corresponds to the helical portion 32a and the curved part of 3 corresponds to the transition curve portion 32?).

In its opening movement, the bolt first cams back the bolt carrier 2, as previously described; and after leaving the translation curve portion 326, the bolt lug or handle enters a slottedportion 33 of the rear slide 5, whereby it is guided in its reciprocatory movement and prevented'from turning or riding oil the rest position between contacts 17 and 18 (see Fig. 2). When the secondary closing spring 10 has thus been sufficiently compressed, the rear slide 5 takes up the rearward movement of the bolt and eventually the bolt carrier 2 is completely collapsed into the rear slide '5 and together with the bolt the assembly travels to the rearmost position, compressing the primary closing spring 6 and fetching up against the cushion of the to com ress the 'same when the lever is swung rom a vertlcal to a horizontal posibuffer spring 34 or the ,rear wall" of the re ceiver.

Buffer spring The buffer spring is a heavy flat spring, doubled once upon itself like a hairpin (see Fig. 14) and is positioned in the receiver under an initial tension by means ofa cam retaining lever 35 pivoted at 36 on the receiver. The lever 35 has an eccentric head 37 which cams against the lower leg of the spring tion in the assembly of the parts. The lever 35 is retained in its horizontal position by the pivot pin 38 of the trigger 39 which is mounted in the receiver and passes through a hole in said lever 35.

It will be noted that the rear upper end 340 of the spring 34 is inclined to the bottom of the bolt carrier so that the spring is compressed by the action of w edging surfaces when the bolt carrier moves to the rear. The inclination of said spring portion 34a is such as to aiford a very eflicient working angle for the bottom of the bolt carrier in compressing the spring, and therefore a very strong tension may be provided in said buifer spring for gradually bringing said bolt carrier to a stop. On the other hand, the return force of the buffer spring acts through a Very ineflicient working angle for imparting forward movement to the bolt carrier, and therefore will give little or no rebound thereto. In other words, the buffer spring is arranged to readily absorb with a yielding opposition most of the surplus energy of the bolt carrier and then dissipate most of this. energy in friction instead of returning it for the forward motion of the bolt carrier.

This result is attained by making the angle of inclination of the spring portion 34a to the bottom of'the bolt carrier 2 only slightly above the angle of repose for said surfaces when unlubricated. Such an angle of repose will be about 15 and the working angle of the spring in tending to move the bolt carrier forward, viz. the inclination of the spring portion 34a to the bottom of the bolt carrier, is preferably madeabout 20 so as to provide a slight factor of safety in preventing any possibility of the bolt carrier sticking at the rear under the pinching action of the buffer spring.

' Bolt stop and follower mechanism The rear movement of the bolt, bolt carrier and rear slide is immediately followed by a return forward movement thereof under the power of the closing springs, which forward movement of the bolt accomplishes the load ing of a fresh cartridge from the magazine in the usual manner. In the event of the magazine being empt or in other words after the last cartridge rom the magazine has been I fired, the return movement of the bolt is prei open well in the receiver and, in the embodiment shown, is adapted to be charged with cartridges from a strip type of cartridge clip. In the charging operation, the cartridge clip will rest against the side shoulders 41 and 42 at the top of the magazine chamber 40, while the cartridges will be stripped there from in the usual manner into said chamber. The cartridges will lie in the the chamber in a double row stack and in staggered relation. The shoulders 41 and 42 slightly overhang the chamber space so as to properly confine the stacked cartridges therein and permit one cartridge at a time to protrude through the top of the chamber, alternately from each row for being loaded by the bolt.

The cartridge feeding follower 43 has a stepped upper surface for engaging the bottom of the staggered rows of the cartridge stack, and is supported for a positively controlled, definitely prescribed movement in the magazine, as distinguished from the usual type of floating follower. Such a support for the follower will facilitate the charging of cartridges into the magazine and also maintain the proper feeding alignment of the cartridges for loading.

In the embodiment shown, crossed levers support the follower. The forward lever 44 is pivoted at 45 on the receiver and at 46 to the rear end of the follower. The rear lever 47 is also the actuating lever and is pivoted to the receiver at 48 and to the forward end of the follower by pin 49. This forward pivotal connection is also a sliding connection, for the pin 49 is slidably received in a slot 50 of the follower. The crossed portions of the levers 44 and 47 are interconnected by a pin 51 in lever 44 working in slot 52 of lever 47. The actuating lever 47 is impelled by spring 53, as shown in Fig. 28.

Pivoted at 54 on the receiver is a bolt stop actuator 55 having a lower arm 56 adapted for engagement by the actuating lever 47 and an upper forked arm 57 for embracing pin 58 on the bolt stop 59. The bolt stop is pivoted to the receiver at 60 and when rocked clockwise is adapted to engage in front of the lug 25 on the bolt and hold the bolt and its associated parts in the position shown in Fig. 4.

In the working operation of the gun with cartridges in the magazine, the follower is held depressed from the position in Fig. 4 and the lever 47 is spaced from arm 56 of the bolt stop actuator, as shown in Fig. 5. The bolt stop actuator 55 may then rock clockwise and withdraw the bolt stop 59 from the path of the bolt lug 25, and thus leave the bolt free for its reciprocatory movement. Under such conditions, the bolt stop actuator will be held in its clockwise rocked position by the pressure of a finger 64 hearing on a flatted shoul course, the effect of spring 53 is greater than the pressure of finger 64 and the bolt stop will be actuated to its holding position as soon as the last cartridge leaves the magazine.

Fz'fing mechanism The hammer 63 is pivoted at on the receiver (on the same pivot as the bolt stop) and is of the configuration shown. in Fig. 18. 65 is the striking face of the hammer which hits the end of the firing pin 66, and side wings 67 of the hammer serve as cocking abutments since they are engaged by the cocking shoulders 68 of the bolt carrier 2 for cocking the hammer when the rotation of the bolt cams the bolt carrier rearwardly as previously described. The hammer is completely cocked when the bolt completes its 90" rota-,

tion, and is held in cocked position by a sear 69 whose sear hook 70 engages the sear notch 71 on the back of the hammer. tail portion 72 is formed at one side of the hammer to ride beneath a heel portion 73 of the sear hook 70 to prevent any immediate forward movement of the sear after the hammer is released. Only when the hammer is again in cocked position will the heel portion 73 ride off the front end of the tail 72 and permit re-engagement of the sear. The sear 69 is pivoted on the receiver at 74 and has a rear forked portion 75 for engagement with the forward end of the trigger 39 pivoted at 38 on the receiver. At the rear of the finger portion of the trigger is a blade projection 76 adapted to normal y work into a slot 77 of a. P

safety bar 78 (see Fig. 6). It will be understood that the safety bar is mounted in the receiver for a transverse adjustable movement and that when set with its slot 77 out of register with the trigger blade 76, the trigger can not be pulled and the firing mechanism will be at Safety. A particular purpose of the hammer tail portion 72 and sear hook heel portion 7 3 will now be apparent, for-if, after releasing the hammer, the sear could immediately rock forward again to its sear engaging position, then any misplacement of the safety bar 78 to safe position while the hammer was forward would prevent the rocking back of the sear; and if the hammer were recocked, a breakage would result.

The hammer spring indicated at 79 serves as the impelling spring for the hammer, sear -and trigger as well as restoring spring for the bolt stop in the following manner. The hammer spring is carried and partially housed in a bridge member 62 (see Fig. 20)

An arcuateand surrounds a spring guide or thrust rod 80 (see Fig. 19), the upper end 81 of which has a pivotal thrust bearing engaging the'boss 82 of the hammer. The bridge member 62 is not pivoted or fastened to the receiver but is ided therein against displacement in a eating manner. A rear projection 83 of said bridge member is slotted to straddle a guiding web 84 (see Fig. 1) ofthe receiver and the left side of projection 83 bears downwardly upon right leg 85 of the sear 69 to give said sear its tendency to rock clockwise The forward projection or finger 64 on the bridge member rests, as before stated, on the shoulder 61 of the bolt stop actuator, and a forward fin 86 on the bridge member has a guiding engagement with a slotted portion of the receiver (see Fig. 1- Thus it will be seen that the bridge mem r distributes the force of its hammer spring upwardly to the hammer and downwardly in the manner of an equalizer bar to the sear and bolt stop actuator. v

The resent gun is designed for semi-automatic re, that is the trigger must be separately pulled for each shot. 'An escapement is therefore provided between the trigger and sear, and the hammer to require a release of the trigger and a repulling of the same for each successive shot. The action of the es capement will be clear from Figs. 26 and 27. Below the sear notch 71 on the rear of the hammer is the escapement notch 87 adapted to be engaged by a second leg 88 of said sear (see Fig. 17).

If a continued pull is maintained on the trigger 39, the hammer, in returning to cocked sition, will force its way pastthe end of leg 88 into the position shown in Fig. 26, wherein as long as the trigger is kept pulled the leg 88 will hold the hammer cocked. As soon as the trigger pull is relieved with the parts in the position of Fig. 26, the sear will rock forward to release leg 88 from escapein Fig. 27.

The firing pin 66 is mounted in an axial bore of the bolt, as shown in Fig. 13. Its

.rear end normally protrudes from the rearv of the bolt under tension of a spring 90 which also serves to actuate into forward position.

the ejector plunger 91. The ejector plunger consists of hollow telescoping cylinder parts containing the spring 90 and having a stop lug 92 extending through a perforation 93 in the bolt wall which is wide at its rear end to permit a slight turning of the longer 91 when retracted. As shown in ig. 12, the plunger hole is enlarged at one side at 94 to allow withdrawal of the plunger and its spring when in turned osition.

The rear portion of t e firing pin 66 has lateral retaining lugs 95 which bear againit an interior shoulder 89 of the bolt. When the firing pin is turned to register the lugs 95 with slots 96 of the'bolt, the firing pin may be withdrawn from the bolt.

The shell extractor 97 is mounted for slide able movement across the rim of the bolt face and has a hooked portion for engaging the groove in the base of the cartridge C. The outer portion of the extractor has a T-way slide mounting in the front side of the bolt lug 14, and the extractor is yieldingly held inward for engagement with the cartridge groove by a spring 98 acting h'rough a tapered headed plunger 99 hearing in a cam recess 100. at the rear of the extractor; It will be understood that when the extractor 97 withdraws an empt shell from the barrel, 1 he ejector plunger 91- icks the shell upwardly out of the receiver.

What I claim is: K

.1. In an automatic bolt action gun, in combination, a receiver, a rotary bolt therein having a projecting handle to provide alarge moment of inertia for" said bolt, locking means for said bolt comprising a locking lug on said bolt, a locking cam in said receiver having a helical bearing surface with a helix angle of approximately 30, theradius-of gyration of said bolt and handle extending beyond said bearing surface and outside of said receiver.

2. In an automatic bolt action gun, in combination, a receiver, a rotary and reciproca- -tory bolt therein having a projecting handle to provide a large moment of inertia for said bolt, locking means for said bolt comprising a lockin lug on said bolt, a locking cam in said receiver having a helical bearing surface with 'ahelix-angle of approximately 30 for contact with one side of said bolt lug'and a guiding surface in said receiver for contact with the other side of said bolt lug during the transition of said bolt from rotary to rectilinear movement, the-radius of gyration of said bolt and handle extending beyond said bearing surfaces and outside of said receiver.

3. In an automatlc bolt action gun, 1n combination, a receiver, a bolt having a rotary and a rectilinear movement therein, a guiding surface in said receiver wall for guiding the transition of said bolt from its rotary to its rectilinear movement,'said guiding surface. comprising a helical portion fairing into a transition curve ortion which corresponds to the path cut y the intersection of the radius ofgyration of said bolt with the wall of the receiver when the projected path of said bolt at the extremity of its radius of gy ration is the are of a circle.

4. In an automatic bolt action gun, in combination, a receiver, a bolt having a rotary and a rectilinear movement therein, locking means for said bolt comprising' a helical'bearing surface in said receiver, said receiver also having a guiding surface in its wall for guiding. the transition of said bolt from its rotary to its rectilinear movement, comprising a helical portion fairing into a transition curve portion which corresponds to ihe path cut by the intersection of the radius of gyration of said bolt with the wall of the receiver when the projected path ofsaid bolt at the extremity of its radius of gyration is the arc of a circle.

5. In an automatic bolt action gun, in combination, a receiver, a bolt having a rotary movement through approximately 90 of rotation terminating in a rectilinear movement therein, said receiver wall having a guiding surface for guiding thetransition of said belt from its rotary to its rectilinear movement comprising a helical portion for guiding approximately of said bolt rotation and a transition curve portion for guiding the remainder of said bolt rotation, said transition curve portion in the receiver wall corresponding to the path cut by the intersection of the radius of gyration of said bolt with the wall of the receiver when the projected path of said bolt, at the extremity of its radius of gyration is the arc of a circle.

. 6. In an automatic bolt action gun, in combination, a receiver,'a bolt having a rotary movement through approximately 90 of rotation terminating ina rectilinear movement therein, locking meansfor said bolt compris ing a helical bearing surface in said receiver, the helix angle ofwhich is approximately 30, said receiver having a guiding surface in its wall for guiding the transi ion of said bolt from its rotary to its rectilinear move ment comprising a helical portion for guiding approximately 70 of said bolt rotation and a transition curve portion for guiding the remainder of said bolt rotation, said transition curve portion in the receiver wall corresponding to'the path cut by the intersection of the radius of gyration of said bolt with the. wall of the receiver when the projected path of said bolt at the extremity ofits radius of gyration is the arc of a circle.

7. In a gun, the combination with a breech action comprising a reciprocatory member. of a single flat buffer spring arranged to readily absorb ener from the rearward movement of said mem er and to restore only a small part of said energy for the forward movement of said member, and retaining means for said spring comprising a cam lever for placing said spring under initial tension.

8. In a gun, the combination with a breech action comprising a reciprocatory member, of a spring actuated bufi'er arranged to receive the blow of said rearwardly moving member through wedging surfaces, the working angle of said wedging surfaces for the return force of said buffer spring belng close o the angle of repose.

9. In a gun, the combination with a breech action comprising a reciprocating member, of a spring actuated bufier arranged to reccivc the blow of said rearwardly moving member through wedging surfaces, the working angle of said wedging surfaces for the return force of said bufi'erspring being approximately 20.

10. In a gun, the combination with a breech action comprising a reciprocating member, of a buffer comprising a fiat spring having a portion extending into the path of said member at an inclination of approximately 20 to said path.

11,. In a gun, the combination with a breech action comprising a reciprocating member, of a buffer comprising a flat spring having a portion extending into the path of said moving member at an inclination of approximately 20 to said path, and retaining means for said spring arranged to place said spring under initial tension.

12. In an automatic bolt action gun, in combination, a receiver, a bolt adapted to be opened by the direct application of the backward pressure of firing, closing means for said bolt comprising two slides mounted in collapsible relation in said receiver, and a separate closing spring for each slide.

13. In an automatic bolt action gun, in combination, a receiver, a bolt ada ted to be opened by the direct application 0 the backs ward pressure of firing, closing means for said bolt comprising a rear slide and a for- Ward slide mounted in collapsible relation in said receiver, a closing spring between said two slides and a closing spring between said rear slide and said receiver.

1 14. In an automatic bolt action gun, in combination, a receiver, a bolt adapted to be opened by the direct application of the backward pressure of firing, locking means for said bolt comprising a helical bearing surface in said receiver, closing means for said bolt comprising a rear slide and a forward slide mounted in collapsible relation in said receiver, helical driving surfaces between said bolt and forward slide, and a separate closing spring for each slide.

15. In an automatic bolt action gun, in combination, a receiver, a bolt having a rotary and reciprocatory movement therein, a handle projecting laterally from said bolt, closing means for said bolt comprising a slide mounted in said receiver and having a-slotted portion to receive the handle of said bolt and prevent the rotation of said bolt during a reciprocatory movement thereof.

16. In an automatic bolt action gun, in combination, a receiver, a bolt having a rotary and reciprocatory movement therein and adapted to be opened by the direct application of the backward pressureof firing, locking means for said bolt comprising a helical bearing surface in said receiver, and awei hted handle projecting laterally from said bolt so that its moment of inertia preventsntoo rapid opening of said bolt, closing means for said bolt comprisinga rear slide and a forward slide mounted in collapsible relation in said receiver, said forward slide having a driving connection with said bolt, and said rear slide having a slotted portion to receive the handle of said bolt and prevent the rotation of said bolt during a reciprocatory movement thereof.

17. In an automaticbolt action gun, in combination, a receiver, a bolt havin a rotary and reciprocatory movement t erein and adapted to be opened by the direct application of the backward pressure of firing, locking means for said bolt comprising a helical bearing surface in said receiver and a coacting lug at the forward end of said bolt,

and a weighted handle projecting laterally as afcontinuation of said lug so that its moment of inertia prevents too rapid opening of said bolt.

18. In an automatic bolt action gun, in combination, a receiver, a bolt having a ro tary and reciprocatory movement and adapted to be opened by the direct application of the backward pressure of firing, locking means for said bolt comprising a helical bearing surface in said receiver and a coacting lug at the forward end of said bolt, a weighted handle projecting laterally as a continuation of said lug so that its moment of inertia prevents too rapid opening of said bolt, and closing means for said bolt comprising a slide mounted in said receiver and having a slotted portion to receive the handle of said bolt and prevent the rotation of said bolt during a reciprocatory movement thereof.

19. In an automatic bolt action gun, in combination, a receiver, a boltadapted to be opened by the direct application of the backward pressure of firing, closing means for said bolt comprising a rear slide and a forward slide mounted in collapsible relation for reciprocatory sliding movement in said receiver, a firing pin in said bolt, a hammer pivoted in said receiver and adapted to be rocked into cocked position by the rearward movement of said bolt closing means.

20. In a bolt action gun, in comb nation, a receiver, a bolt having a rotary and reciprocatory movement-therein, a slide in said receiver, coacting cam surfaces between said III receiver, coacting cam surfaces between said bolt and slide for retracting said slide by the rotation of said bolt, a hammer pivoted in said receiver having a striking face and cooking ears projecting forwardly thereof, said slide having cocking shoulders for engaging said cooking ears and thereby cock said hamnlle upon said retracting movement of said s 1 e.

22. In an automatic bolt action gun, in combination, a receiver, a bolt having a rotary and a reciprocatory movement therein and adapted to be opened by the direct application of the backward pressure of firing, closing means for. said bolt comprising a rear slide and a forward slide mounted in collapsible relation in said'receiver, closing springs for said slides, coacting cam surfaces between said bolt and said forward slide for retracting said slide by the rotation of said bolt, a hammer pivoted in said receiver for engagement by said forward slide and arranged to be cocked by said retracting movement of said slide.

23. In the firing mechanism of a gun, in combination, a bolt, a hammer, a hammer spring therefor, a sear, a bolt stop and actuator therefor, a carrier for said hammer spring positioned as an equalizer bar for distributing actuating force both to said scar and to said bolt stop actuator for the independent operation of said parts.

24. In the firing mechanism of a gun, in combination, a hammer, a sear for holding said hammer in cocked position, a trigger connected to move with the sear both in releasing and in holding the hammer, and a safety adjustable in position to prevent the movement of said trigger and sear, said hammer having a stop for engagement by said sear when released from its hammer holding I position to thereby prevent a return of the trigger and sear to safety enga'geable position until the hammer is again cocked.

25. In the breach action of a gun in combination, a receiver, a rotary and reciprocatory bolt therein, means for locking said bolt to the breech adapted'to be automatically unlocked by the firing pressure, comprising helical bearing surfaces on said bolt and receiver adapted for coacting engagement, the helix angle of said bearing surfaces being tory bolt therein, means for locking said bolt to the breech adapted to be automatically unlocked by the firing pressure, comprising helical bearing surfaces on said bolt and receiver adapted for coacting engagement, the helix angle of said bearing surfaces being approximately twice the angle of repose for said surfaces when unlubricated, said bolt being formed with such distribution of its mass as to have a radius of gyration considerably longer than the radius of said helical bearing surfaces.

28. In the breech action of a gun in combination, a receiver, a rotary and reciprocatory bolt therein, means for locking said bolt to the breech adapted to be automatically unlocked by the firing pressure, comprising helical bearing surfaces on said bolt and receiver adapted for coacting engagement, the helix angle of said bearing surfaces being approximately twice the angle of repose for said surfaces when unlubricated, said bolt having an abnormally wei hted portion projecting radiall outside 0 said receiver so as to give sai bolt a radius of gyration considerably longer than the radius of said helical bearing surfaces.

29. In the breech action of a gun in combination, a receiver, a rotary and reciprocatory bolt therein, means for locking sai bolt to the breech adapted to be automatically unlocked by the. firing ressure, comprising helical bearing sur aces on said bolt and receiver adapted for coacting engagement, the helix angle of said bearing surfaces being approximately twice the angle of repose for said surfaces when unlubricated, and a radially rojecting handle on said bolt having an a normally wei hted outer end so as to give said bolt a radlus of gyrationconsiderably longer than the radius of said helical bearing surfaces. In testimony whereof I have aifixed my signature.

JOHN D. PEDERSEN.

approximately twice the angle of repose for said surfaces when unlubricated.

26. In the breech action of a an in combination, a receiver, a rotary an reciprocatory bolt therein, means or locking said bolt to the breech adapted to be automatically unlocked by the firing pressure, comprising helical bearing surfaces on said bolt and receiver adapted for coacting engagement, the helix angle of said bearing sur-, faces being approximately 30.

27. In the" breech action of a gun in combination, a receiver, a rotary and reciproca- 

